Development
Statue of John Ericsson in Battery Park, New York City, holding a model of Monitor in his hand

After the United States received word of the construction of the Virginia, Congress appropriated $1.5 million on 3 August to build one or more armored steamships. It also ordered the creation of a board to inquire into armored ships. The U.S. Navy advertised for proposals for "iron-clad steam vessels of war"[2] on 7 August and Gideon Welles, the Secretary of the Navy, appointed the three members of the Ironclad Board the following day. Their task was to "examine plans for the completion of iron-clad vessels".[2]

Ericsson originally made no submission to the board, but became involved when Cornelius Bushnell, the sponsor of the proposal that became the armored sloopUSS Galena, needed to have his design reviewed by a naval constructor. The board required a guarantee from Bushnell that his ship would float despite the weight of its armor and Cornelius H. DeLamater recommended that Bushnell consult with his friend John Ericsson. The two first met on 9 September and again on the following day, after Ericsson had time to evaluate Galena's design. During this second meeting Ericsson showed Bushnell his own design, the future Monitor. Bushnell got Ericsson's permission to show the model of his design to Welles and the latter told Bushnell to show it to the board. Despite a preliminary rejection, the board accepted Ericsson's proposal after he explained his design in person on 15 September.[3] The Ironclad Board evaluated 17 different designs, but recommended only three on 16 September.[4] The name "Monitor" was proposed by Ericsson and approved by Assistant Secretary of the Navy Gustavus Fox.[5]

The three ironclad ships differed substantially in design and degree of risk. The Monitor was the most innovative design by virtue of its low freeboard, shallow-draft iron hull, and total dependence on steam power. The riskiest element of its design was its rotating gun turret,[6] something that had not previously been built or tested by any navy.[b] Ericsson's guarantee of delivery in 100 days proved to be decisive in choosing his design despite the risk involved. The wooden-hulled Galena's most novel feature was her armor of interlocking iron rails. The armored frigateUSS New Ironsides was much influenced by the French ironclad Gloire and was the most conservative design of the three, which copied many of the features of the French ship.[6]

Design and description

Described by critics as a "cheesebox on a raft,"[8] as the Monitor's most prominent feature was a large cylindrical gun turret mounted amidships above the low-freeboard upper hull, also called the "raft". This extended well past the sides of the lower, more traditionally shaped hull. A small, armored pilot house, was fitted on the upper deck towards the bow. One of Ericsson's prime goals in designing the ship was to present the smallest possible target to enemy gunfire.[9]

The ship was 179 feet (54.6 m) long overall, had a beam of 41 feet 6 inches (12.6 m) and had a maximum draft of 10 feet 6 inches (3.2 m). The Monitor had a tonnage of 776 tons burthen and displaced 987 long tons (1,003 t). Her crew consisted of 49 officers and enlisted men.[10]

The Monitor was powered by a single-cylinder horizontal vibrating-lever steam engine,[11] which drove a 9-foot (2.7 m) propeller.[9] The engine used steam generated by two horizontal fire-tube boilers[12] at a maximum pressure of 40 psi (276 kPa; 3 kgf/cm2).[13] The 320-indicated-horsepower (240 kW) engine was designed to give the ship a top speed of 8 knots (15 km/h; 9.2 mph), but the Monitor was 1–2 knots (1.9–3.7 km/h; 1.2–2.3 mph) slower in service.[11] The engine had a bore of 36 inches (914 mm) and a stroke of 22 inches (559 mm).[10] The ship carried 100 long tons (100 t) of coal.[11] Ventilation in the Monitor was supplied by two centrifugal blowers near the stern, each of which was powered by 6-horsepower (4.5 kW) steam engine. One fan circulated air throughout the ship, but the other one forced air through the boilers, which depended on this forced draught. Leather belts connected the blowers to their engines and they would stretch when wet, often disabling the fans and boilers. The ship's pumps were steam operated and water would accumulate in the ship if the pumps could not get enough steam to work.[9]

The top of the armored deck was only about 18 inches (460 mm) above the waterline. It was protected by two layers of 1⁄2-inch (13 mm) wrought iron armor. The sides of the "raft" consisted of three to five layers of 1-inch (25 mm) iron plates, backed by about 30 inches (762 mm) of pine and oak. Three of the plates extended the full 60 inches (1,524 mm) height of the side, but the two innermost plates did not extend all the way down. Ericsson originally intended to use either six 1-inch plates or a single outer 4-inch (100 mm) plate backed by three 3⁄4-inch (19 mm) plates, but the thicker plate required too much time to roll.[14] Glass portholes in the deck provided natural light for the interior of the ship; in action these were covered by iron plates.[9]

A computer model of the Monitor

Ericsson initially planned to use four-inch iron plates, backed by several thinner plates, for the turret, but the inability to get such thick plates in a timely manner forced him to switch to eight layers of one-inch plate. The two innermost plates were riveted together while the outer plates were bolted to the inner ones. A ninth plate, only 3⁄4 inches (19 mm) thick and 15 inches (381 mm) wide, was bolted over the butt joints of the innermost layer of armor. The entire weight of the turret rested on an iron spindle that had to be jacked up using a wedge before the turret could rotate. When not in use, the turret rested on a brass ring that was intended to form a watertight seal. In service, however, this proved to leak heavily, despite caulking by the crew.[15]

Monitor's turret was intended to mount a pair of 15-inch (380 mm) smoothboreDahlgren guns, but they were not ready in time and 11-inch (280 mm) guns were substituted.[16] Each gun weighed approximately 16,000 pounds (7,300 kg). They could fire a 136-pound (61.7 kg) shell up to a range of 3,650 yards (3,340 m) at an elevation of +15°.[17]

Construction and service

Monitor's hull was built at the Continental Iron Works in the Greenpoint section of Brooklyn, New York, and the ship was launched there on 30 January 1862. The innovative vibrating lever, or half-trunk, steam engines, designed by John Ericsson, and machinery were constructed at the DeLamater Iron Works in Manhattan.[18]

Battle of Hampton Roads
Main article: Battle of Hampton Roads
USS Monitor in action with CSS Virginia, 9 March 1862

On 8 March 1862, CSS Virginia attacked the Union blockading squadron in Hampton Roads, Virginia, destroying the sail frigates Cumberland and Congress. Early in the battle, the steam frigate Minnesota ran aground while attempting to engage the Virginia, and remained stranded throughout the battle. Virginia, however, was unable to attack the Minnesota before daylight faded.

That night, Monitor — under command of Lieutenant John L. Worden — arrived from Brooklyn after a harrowing trip under tow. When Virginia returned the next day to finish off Minnesota and the rest of the blockaders, Monitor moved out to stop her. The ironclads fought at close range for about four hours, neither one sinking or seriously damaging the other. At one point, Virginia attempted to ram, but she only struck Monitor with a glancing blow that did no damage. It did, however, aggravate the damage done to Virginia's bow from when she had previously rammed the Cumberland. Monitor was also unable to do significant damage to Virginia, possibly due to the fact that her guns were firing with reduced charges as ordered by Commander John Dahlgren, the gun's designer.[18]

Towards the end of the engagement, Virginia was able to hit Monitor's pilothouse. Lt. Worden, blinded by shell fragments and gunpowder residue from the explosion, ordered Monitor to sheer off into shallow water. Command passed to the executive officer, Samuel Greene, who assessed the damage and ordered Monitor to turn around back into the battle.

Virginia, seeing Monitor turn away, had turned her attention back to Minnesota. The falling tide, however, prevented her from getting close to the stranded warship. After an informal war council with his officers, Virginia's captain decided to return to Norfolk for repairs. Monitor arrived back on the scene as Virginia was leaving. Greene, under orders to protect Minnesota, did not pursue.

Tactically, the battle between these two ships was a draw, though it could be argued that Virginia did slightly more damage to Monitor than Monitor to Virginia. Monitor did successfully defend Minnesota and the rest of the U.S. blockading force, while Virginia was unable to complete the destruction she started the previous day. Strategically, nothing had immediately changed: the Federals still controlled Hampton Roads and the Confederates still held several rivers and Norfolk,[19] making it a strategic victory for the North.

Events after the battle

Both Union and Confederates came up with plans for defeating the other’s ironclad. Oddly, these did not depend on their own ironclads. The Union Navy chartered a large ship (the sidewheelerVanderbilt) as a naval ram, provided Virginia steamed far enough out into Hampton Roads. The Confederate Navy made plans to swarm aboard and capture Monitor using the four gunboats of the James River Squadron. On 11 April, Virginia steamed out to Sewell’s Point at the southeast edge of Hampton Roads in a challenge to Monitor.

The Monitor on the James River, Virginia, in 1862, after the Battle of Hampton Roads. Note the dents in the armor on the turret.

In an attempt to lure Monitor closer to where she could be boarded, Virginia stood out into the Roads and almost over to Newport News. However, Monitor stayed near Fort Monroe, ready to fight if Virginia came to attack the Federal force which had congregated there. Furthermore, Vanderbilt would be in a position to ram Virginia if she approached the fort. Virginia did not take the bait. In a further attempt to entice Monitor closer to the Confederate side so she could be boarded, the James River Squadron moved in and captured three merchant ships, the brigs Marcus and Sabout, and the schooner Catherine T. Dix. These had been grounded and abandoned when they sighted Virginia entering the Roads. Their flags were then hoisted "Union-side down" to taunt Monitor into a fight as they were towed back to Norfolk. In the end both sides had failed to lure the other out for a fight on their terms.

A second meeting occurred on 8 May, when Virginia came out while Monitor and four other Federal ships bombarded Confederate batteries at Sewell’s Point. The Federal ships retired slowly to Fort Monroe, hoping to lure Virginia into the Roads. She did not follow, however, and after firing a gun to windward as a sign of contempt, anchored off Sewell’s Point. However, she was forced to scuttle when Confederate forces abandoned Norfolk three days later.

After the destruction of Virginia, Monitor was free to assist McClellan's campaign against Richmond. On 15 May 1862, the ironclad and four other gunboats steamed up the James River and engaged Confederate batteries at Drewry's Bluff. Monitor's guns, however, could not elevate sufficiently to engage the batteries at close range, and the other gunboats were unable to overcome the fortifications on their own. The engagement ended when the Union fleet retired after four hours of bombardment.[18]

Loss at sea
Engraving of Monitor sinking

While the design of Monitor was well-suited for river combat, her low freeboard and heavy turret made her highly unseaworthy in rough waters. This feature probably led to the early loss of the ship, which foundered during a heavy storm. She sank on 31 December 1862 off Cape Hatteras; sixteen of her 62-member crew were either lost overboard or went down with the ironclad, while many others were saved by boats sent from Rhode Island.

Rediscovery

In 1951, retired Rear Admiral Edward Ellsberg proposed using external pontoons to raise the Monitor, the same method of marine salvage he had used on the sunken submarine S-51. Ellsberg estimated the project would cost $250,000.[20] No action was taken on the proposal. In August 1973, the wreck of the ironclad Monitor was located on the floor of the Atlantic Ocean about 16 nautical miles (30 km; 18 mi) southeast of Cape Hatteras, North Carolina. The wreck site was designated as the first U.S. marine sanctuary.[21] The Monitor National Marine Sanctuary is the only one of the thirteen national marine sanctuaries created to protect a cultural resource, rather than a natural resource.

In 1986, Monitor was designated a National Historic Landmark. It is one of only four accessible monitor vessels in the world, the others being the Australian vessel HMVS Cerberus, the wreck of the Norwegian Thor, which lies at about 25 ft (7.6 m) off Verdens Ende in Vestfold county, Norway, and the British vessel Hellman.

The U.S. Navy interest in raising the entire ship ended in 1978 when Willard F. Searle, Jr. calculated the cost and possible damage expected from the operation: $20 million to stabilize the vessel in place, or as much as $50 million to bring all of it to the surface.[22] However in 1998 the warship's propeller was raised to the surface.[22] On 16 July 2001, divers from the Monitor National Marine Sanctuary and the US Navy brought to the surface the 30-metric-ton (30-long-ton) steam engine. Due to the depth of the wreck, the divers utilized surface supplied diving techniques while breathing heliox.[23] In August 2002, after 41 days of work, the revolutionary revolving gun turret was recovered by the U.S. National Oceanic and Atmospheric Administration (NOAA) and a team of U.S. Navy divers. Before removing the turret, divers discovered the remains of two trapped crewmen. The remains of these sailors,[24] who died while on duty, were temporarily stored at the Joint POW-MIA Accounting Command (JPAC) at Hickam Air Force Base, Hawaii, awaiting positive identification. Among the most promising of the 16 candidates are crew members Jacob Nicklis, Robert Williams and William Bryan.[25][26][27][28] A decade passed without their identities being known. On 8 March 2013, their remains will be buried at Arlington National Cemetery with full military honors.[29]

The site is now under the supervision of NOAA. Many artifacts from Monitor, including her turret, cannon, propeller, anchor, engine and some personal effects of the crew, have been conserved and are on display at the Mariners' Museum of Newport News, Virginia.[30] Artifact recovery from the site has become paramount, as the wreck has become unstable and will decay over the next several decades; this fate also awaits many other well known wrecks of iron and steel ships, such as Titanic and Lusitania.

In 1996 a Greenpoint Monitor Museum was chartered, hoping to display the ship near her launch site.[31]

Northrop Grumman in Newport News constructed a full-scale non-seaworthy static land-bound replica of USS Monitor. The replica was laid down in February 2005 and completed just two months later.[32]

Monitor became the prototype for a new warship type dubbed "monitor" after the original. Many more were built, including river monitors and deep-sea monitors, and they played key roles in Civil War battles on the Mississippi and James Rivers. Some had two or even three turrets, and later monitors had improved seaworthiness. Many designs had a rounded deck so fragmentation from enemy fire would ricochet, rather than penetrate.

After the war ended, Stepping Stones was decommissioned at the Washington Navy Yard on 23 June 1865 and was sold on 12 July 1865 to W. D. Wallach. Redocumented as Cambridge on 27 July 1865, the steamer was reduced to a barge on 2 August 1871 and soon disappeared from maritime records.